A very large deal was made of the Dwarves and Bilbo relinquishing Beorn's ponies when they reached the eaves of Mirkwood, however Gandalf kept the Horse provided to him by Beorn? Does this indicate Beorn knew of or was made aware by Gandalf of his larger mission in dealing with the Necromancer? Could Beorn then been involved and could his arrival at the Battle of Five Armies been partly due to more recent dealings with Gandald then Queer Lodgings?

...is that Gandalf rode the horse back to Beorn's place before proceeding south. However, it is also possible that Gandalf told Beorn of his need for haste and that he was allowed to borrow his steed for a more extended period. 'There are older and fouler things than Orcs in the deep places of the world.' - Gandalf the Grey, The Fellowship of the Ring

Beorn provides horses, but they must be returned, and Gandalf says he is not 'sending' his horse back, but riding it back, implying, at least, that he will return this horse. But did Beorn allow Gandalf to ride beyond this? If memory serves there is no mention of any steed when Gandalf first appears, later in the tale.

We are then told Bilbo and Gandalf 'rode' behind the Elvenking, while beside them 'strode Beorn', so I assume someone had given them steeds, seemingly ponies, as (The Last Stage) it is noted 'their ponies were tired, especially the one that carried the baggage'. And ponies again after Rivendell, as: 'So they put the gold in bags and slung them on their ponies...'Hmm. Well, as far as the horses go anyway...

I would agree with that, and add that Beorn may have been more concerned with the dwarves taking his ponies into Mirkwood and risk having them die there for any number of reasons (including as meals for hungry dwarves). Gandalf wasn't taking his horse into harm's way, so he was probably given more latitude with it. Being a wizard gave him more status, too.

I'm not sure where the White Council met to drive Sauron out of Dol Guldur, but Lorien seems the likely spot since it was closest to the threat. If Gandalf told Beorn he was going to Lorien, which wasn't too far off, he might have been allowed to go there and release the horse, then get another one from Lorien to go to Esgaroth. Given the distance to Esgaroth, I think he'd need a horse, not a pony. All speculation, of course.

he didn't send his horse back, because he was going to ride it back? Meaning he was going to take the horse and the ponies back to Beorn himself, as Beorn's house was along his way to the south. But every word you say today Gets twisted 'round some other way And they'll hurt you if they think you've lied

Yes Gandalf says he is not 'sending' his horse back, but riding it back, implying (in my opinion at least), that he will return this horse.

That said, Gandalf had a journey before him still, and it would be natural enough to want a horse at this time. I would have to check the text again, but unless there's something that states or implies that Beorn would not continue to lend Gandalf his horse, some are just raising the possibility that maybe he did.

As far as I know the text doesn't say (with respect to riding or walking) what happens after all the steeds are back at Beorn's home. I didn't check Appendix B to see if the wording there might help, but this is all I could find so far (hopefully correct as it is)...

Gandalf and his partial horse history

Third Age 2941: Gandalf visits Bilbo in the Shire. We know that Gandalf rides a white horse (Roast Mutton) at the start of the journey, and this horse is later noted (the 1960 Hobbit) as being named Rohald and 'belonged to Rivendell, & had been lent by Elrond to Gandalf' (Arrival in Rivendell, New Chapter Three, notes, The History of The Hobbit).

Is Rohald an 'Elvish horse'? And if so, what does that mean exactly? Possibly that's a discussion for a later time!

But The Hobbit notes that after Rivendell, Elrond then lent Gandalf a 'jolly sturdy little white fellow' of a pony, since his horse was not suitable for the mountain paths. But these are captured of course. Later Beorn provides horses, but they must be returned, and Gandalf says he is not 'sending' his horse back, but riding it back, implying, at least, that he will return this horse. If memory serves there is no mention of any steed when Gandalf first appears later in the tale.

We are then told Bilbo and Gandalf 'rode' behind the Elvenking, while beside them 'strode Beorn', so I assume someone had given them steeds, seemingly ponies, as (The Last Stage) it is noted 'their ponies were tired, especially the one that carried the baggage'. And ponies again after Rivendell, as: 'So they put the gold in bags and slung them on their ponies...'

Jumping ahead to Third Age 3001 we have Bilbo's farewell feast, and Gandalf visits Frodo in year 3004, and does so at intervals during the next four years.

Tolkien noted (Unfinished Tales) that Gandalf left Thranduil in Mirkwood on 29 March, but after the Carrock he had a horse, and got a fresh horse at Rivendell, and reached Hobbiton on 12 April 3018 [by the way, the dating here is somewhat confused when description from The Hunt for the Ring is considered and compared to Appendix B, but in a carbon copy of the latest typescript of Appendix B, Tolkien tinkered with things, noting that Gandalf 'had a horse for part of the time' Hammond And Scull Appendix B, The Lord of the Rings, A Reader's Companion).

Incidentally I became confused here for a while about the dating, so thanks to Hammond and Scull for revealing that I was not alone (I kept thinking I was missing something)!

Gandalf notes (The Council of Elrond) that 'At the end of June I was in the Shire...' and he meets Radagast (who has a horse) on Mid-years Day. So Gandalf was horsed here and rode out of the Shire to be soon enough imprisoned in Orthanc in July 3018.

I don't have the book with me but isn't it indicated in the text that Beorn was following the party to make sure that they didn't take his ponies into Mirwood? I think it's mentions that Bilbo thought he saw a bear following them out of the corner of his eye and Gandalf basically confirmed it. So there was not need to take the ponies or the horse back to Beorn's house since he was already in the vicinity. JOHNS29

... that Beorn followed the Dwarves and Gandalf notes this, it is still Gandalf who says 'Now you must send back these excellent ponies you have borrowed.' And then Thorin questions Ganadalf about the 'horse' and his promise, and Gandalf says: 'I will look after that. I am not sending the horse back, I am riding it.' And with this they knew Gandalf was leaving them.

So it's Gandalf who still uses the phrasing 'send back' despite that he knows Beorn has followed, and the meaning is still easily enough understood: Beorn is getting his ponies back, they are 'returned' before venturing deep into Mirkwood, and they will end up back at his home.

Gandalf arguably draws the distinction between 'sending' and 'riding' because he is leaving the Dwarves and Bilbo at this point, but to my mind the reader can't tell if Gandalf means he is riding 'back' along with the ponies (which I think is at least implied) to return his horse as well, or if this means he is riding it as in: anywhere else he wants to go.

So in my opinion the distinction you're making here about returning the ponies still leaves the reader wondering the same thing: we don't know if the wizard is going back with Beorn and leaving his horse at Beorn's home, or if Beorn has allowed Gandalf to take the horse to his next destination.

It seems to me that since Thorin questions Gandalf about his promise of not taking his horse into Mirkwood and Gandalf says "I will look after that. I am not sending the horse back, I am riding it.' " the thought conveyed to the reader by the context of that entire scene is not that Gandalf is riding back to Beorn's house but that Gandalf is riding to some place else but is technically keeping his promise to Beorn about not taking the horse into Mirkwood but he's not sending it back to Beorn at that time. And that's the thing he will have to 'look after' with Beorn when the time came. And if I recall correctly the text doesn't say Gandalf went riding back in the direction of Beorn's house when he left the Dwarves party but in a different direction altogether. JOHNS29

You may well be right, I'm just not sure it's certain. Beorn says that he must ask them all to send back his horse and ponies, so he certainly includes the horse in the promise. The later conversation, it seems to me, is Gandalf playing a bit with Thorin's statement: Thorin says 'sending that back' and Gandalf replies he is not sending it...

... to me 'the play' so far is between riding and sending, and 'back' or not is still in question. Thorin then focuses on the promise, which as we know was to return the horse as well, and Gandalf says: 'I will look after that. I am not sending the horse back, I am riding it.'

Well, in my opinion, the way this is phrased one doesn't necessarily have to say 'back' after riding, as it can be implied due to the first part of the sentence; but it may be that Gandalf deliberately does not say back because even if it's implied, it isn't what he means (at least at the moment).

Moreover, as you point out, Gandalf and the ponies are given 'somewhat separate' exits, so to speak, which might imply that he isn't going with the ponies, and thus 'back' to Beorn's house at the moment, and it's actually stated that he rides West -- although on that note, he had already said he had pressing business South.

And as for the ponies, which way did they begin their return? They: 'put their tails towards the Shadow of Mirkwood' and Bilbo thought he saw a 'thing like a Bear left the shadow of the trees and shambled off quickly after them.'

So while I think you interpretation is certainly valid (and even if Gandalf implied 'I am riding it (back)' he might mean at some later point), I'm not sure it's a certainty. Beorn's house was (generally) South of where the company now stood, and I think the main impact of Gandalf's words was that he was now leaving Bilbo and the Dwarves, while leaving it somewhat unclear as to how he was to keep his promise to Beorn about the horse.

At the moment you've got me leaning more toward Gandalf only technically keeping his promise. I mean he could use a horse if his business was pressing; but on the other hand the wizard himself notes that it might be dangerous to cross Beorn, if Beorn wasn't allowing Gandalf any extra room with his promise that is.

Gandalf was prepared to return the horse to Beorn, if necessary. However, his actual intent might have been to catch up to Beorn and urge him to allow the wizard to keep the steed until he could reach his southern destination--at which point he would send the beast back. The statement is written in such a way as to leave it open to interpretation. 'There are older and fouler things than Orcs in the deep places of the world.' - Gandalf the Grey, The Fellowship of the Ring

'Beorn may be your friend, but he loves his animals as his children. You do not guess what kindness he has shown you in letting dwarves ride them so far and so fast, nor what would happen to you, if you tried to take them into the forest.'

To me 'as his children' is pretty strong. Would the importance of his 'new friend' Gandalf's mission be enough to sway Beorn to lend his horse further, if Gandalf pressed the matter? I think Beorn would want a safer Mirkwood...

... but then again he has a strong bond with this horse... hmm... wait I think I'm back in the middle again, on the fence

Although he shows later with King Theoden and Shadowfax that he can be very casual about his interpretation of permissions. 'There are older and fouler things than Orcs in the deep places of the world.' - Gandalf the Grey, The Fellowship of the Ring